Westerdam was built by Fincantieri for Holland America Line.
She is one of four 'Vista Class' ships built for Holland America Line. A near sister, Arcadia, is operated by P&O, Eurodam and Queen Victoria are slightly different version of the same series of ships.
A more detailed technical description of her sister Oosterdam is found at www.ship-technology.com.
Photos of Westerdam are found at Pam Massey's webpage, a review is available at www.cruisepage.com.